The present invention relates to the field of medical imaging, particularly to an apparatus and method for controlling a pulse sequence of a magnetic resonance imaging system.
A magnetic resonance (MR) imaging system includes a radio frequency system and a gradient system. The radio frequency system is used for emitting a radio frequency pulse with a certain frequency and power such that hydrogen protons within a detected object generate a resonance, and for receiving an MR signal generated by the hydrogen protons within the detected object, the MR signal being used for performing image reconstruction on a detected part of the detected object. The gradient system is used for emitting a level selecting gradient pulse, a phase encoding gradient pulse and a frequency encoding gradient pulse (also referred to as a readout gradient pulse) to provide three-dimensional position information for the above MR signal so as to achieve the image reconstruction.
When MR scan imaging is performed, an apparatus for controlling a pulse sequence controls the radio frequency system and the gradient system to emit a desired pulse sequence according to a preset timing to perform the scan imaging on a specific detected part of the detected object.
Diffusion weighted imaging (DWI) is a new MR imaging method, which has been more and more widely used in the field of medical diagnosis. Since in the DWI, the pulse sequence includes two motion probing gradient (MPG) pulses with larger widths and amplitudes applied on a gradient magnetic field coil, whose power consumption takes up a large part of power consumption of the whole DWI imaging, the existing power supply sometimes cannot satisfy the requirements of power consumption. In order to solve the problem of power, in the process of scanning, the operation sometimes needs to stop for a period of time after the two MPG pulses are applied so as to recover the power, which results in a longer scanning time.
Those skilled in the art have attempted to reduce the power consumption by decreasing the amplitudes of the MGP pulses or increasing a time interval between the two MPG pulses. However, such method will increase a time of echo, which will decrease a signal-to-noise ratio significantly and lower the image quality.
Accordingly, there is a need to provide a novel apparatus and method for controlling a pulse sequence of a MR imaging system that can reduce power consumption while ensuring the image quality.